Introducing chemical functionality in Fmoc-peptide gels for cell culture

Acta Biomater. 2009 Mar;5(3):934-43. doi: 10.1016/j.actbio.2009.01.006. Epub 2009 Jan 18.

Abstract

Aromatic short peptide derivatives, i.e. peptides modified with aromatic groups such as 9-fluorenylmethoxycarbonyl (Fmoc), can self-assemble into self-supporting hydrogels. These hydrogels have some similarities to extracellular matrices due to their high hydration, relative stiffness and nanofibrous architecture. We previously demonstrated that Fmoc-diphenylalanine (Fmoc-F(2)) provides a suitable matrix for two-dimensional (2D) or three-dimensional (3D) culture of primary bovine chondrocytes. In this paper we investigate whether the introduction of chemical functionality, such as NH(2), COOH or OH, enhances compatibility with different cell types. A series of hydrogel compositions consisting of combinations of Fmoc-F(2) and n-protected Fmoc amino acids, lysine (K, with side chain R=(CH(2))(4)NH(2)), glutamic acid (D, with side chain R=CH(2)COOH), and serine (S, with side chain R=CH(2)OH) were studied. All compositions produced fibrous scaffolds with fibre diameters in the range of 32-65 nm as assessed by cryo-scanning electron microscopy and atomic force microscopy. Fourier transform infrared spectroscopy analysis suggested that peptide segments adopt a predominantly antiparallel beta-sheet conformation. Oscillatory rheology results show that all four hydrogels have mechanical profiles of soft viscoelastic materials with elastic moduli dependent on the chemical composition, ranging from 502 Pa (Fmoc-F(2)/D) to 21.2 KPa (Fmoc-F(2)). All gels supported the viability of bovine chondrocytes as assessed by a live-dead staining assay. Fmoc-F(2)/S and Fmoc-F(2)/D hydrogels in addition supported viability for human dermal fibroblasts (HDF) while Fmoc-F(2)/S hydrogel was the only gel type that supported viability for all three cell types tested. Fmoc-F(2)/S was therefore investigated further by studying cell proliferation, cytoskeletal organization and histological analysis in 2D culture. In addition, the Fmoc-F(2)/S gel was shown to support retention of cell morphology in 3D culture of bovine chondrocytes. These results demonstrate that introduction of chemical functionality into Fmoc-peptide scaffolds may provide gels with tunable chemical and mechanical properties for in vitro cell culture.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Animals
  • Biocompatible Materials / chemistry*
  • Cattle
  • Cell Adhesion
  • Cell Proliferation
  • Cell Survival
  • Cells, Cultured
  • Chondrocytes
  • Cytoskeleton / metabolism
  • DNA / genetics
  • DNA / metabolism*
  • DNA / ultrastructure
  • Dermis / cytology
  • Elastic Modulus
  • Elasticity
  • Fibroblasts
  • Fluorenes / chemistry
  • Gene Transfer Techniques*
  • Glutamic Acid / chemistry
  • Humans
  • Hydrogels / chemistry
  • Hydrogen Bonding
  • Hydrogen-Ion Concentration
  • Lactate Dehydrogenases / metabolism
  • Lysine / chemistry
  • Mice
  • Nanostructures / chemistry
  • Nanostructures / ultrastructure
  • Peptides / chemistry*
  • Plasmids / genetics
  • Protein Structure, Secondary
  • Serine / chemistry
  • Static Electricity
  • Tissue Scaffolds
  • Viscosity

Substances

  • 9-fluorenylmethoxycarbonyl
  • Biocompatible Materials
  • Fluorenes
  • Hydrogels
  • Peptides
  • Glutamic Acid
  • Serine
  • DNA
  • Lactate Dehydrogenases
  • Lysine